This nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 2001-296436 filed in JAPAN on Sep. 27, 2001, which is herein incorporated by reference.
The present invention relates to an electric power source for supplying an electric power from a battery to an electric power line extending at an outside of the electric power source with boosting a voltage generated by the battery so that the electric power of boosted voltage is supplied to the electric power line.
It is well known that an electric power source for supplying an electric power from a battery to an electric power line extending at an outside of the electric power source with boosting a voltage generated by the battery so that the electric power of boosted voltage is supplied to the electric power line, is electrically connected to the electric power line when the electric power line is active, that is, a voltage of the electric power line is kept at a desirable normal value.
An object of the present invention is to provide an electric power source for supplying an electric power from a battery to an electric power line extending at an outside of the electric power source with boosting a voltage generated by the battery so that the electric power of boosted voltage is supplied to the electric power line, by which electric power source an excessive amount of the electric power supply from the electric power line into the electric power source is restrained even when the electric power source is electrically connected to the active electric power line.
According to the present invention, an electric power source for supplying an electric power from a battery to an electric power line extending at an outside of the electric power source with boosting a voltage generated by the battery so that the electric power of boosted voltage is supplied to the electric power line, comprises, a main switch device operable to switch on and off the electric power supply from the electric power source to the outside of the electric power source, and a voltage booster operable to boost the voltage generated by the battery to generate the electric power of boosted voltage, wherein the main switch device prevents the electric power supply into the electric power line from the electric power source and the electric power supply from the electric power line into the electric power source in a case in which the boosted voltage to be supplied to the electric power line is less than a target voltage not less than a voltage of the electric power line, while allowing the electric power supply into the electric power line from the electric power source when the boosted voltage to be supplied to the electric power line is not less than the target voltage.
Since the main switch device prevents the electric power supply into the electric power line from the electric power source and the electric power supply from the electric power line into the electric power source in a case in which the boosted voltage to be supplied to the electric power line is less than a target voltage not less than a voltage of the electric power line, while allowing the electric power supply into the electric power line from the electric power source and preventing the electric power supply from the electric power line into the electric power source when the boosted voltage to be supplied to the electric power line is not less than the target voltage, an excessive amount of the electric power supply from the electric power line into the electric power source is restrained even when the electric power source is electrically connected to the electric power line being active.
If the electric power source further comprises a detector operable to detect whether or not an electric communication is formed between the electric power source and the electric power line so that the electric power of boosted voltage is allowed to be supplied from the electric power source to the electric power line, and the voltage booster is allowed to boost the voltage generated by the battery to generate the electric power of boosted voltage when the electric communication is formed between the electric power source and the electric power line and is prevented from boosting the voltage generated by the battery to generate the electric power of boosted voltage when the electric communication is not formed between the electric power source and the electric power line, so that the voltage booster starts to boost the voltage after the electric communication is formed between the electric power source and the electric power line, an electric power charged in the battery and/or the voltage booster can be maintained effectively. The voltage booster may include a capacitor for storing the electric power of boosted voltage to be supplied into the electric power line. If the main switch device prevents the electric power supply from the electric power source to the outside of the electric power source (for example, a human body or an electrically grounded member at the outside of the electric power source) and the electric power supply from the electric power line into the electric power source in at least one of a case in which the electric communication is not formed between the electric power source and the electric power line and the case in which the boosted voltage to be supplied to the electric power line is less than the target voltage, while allowing the electric power supply into the electric power line from the electric power source and preventing the electric power supply from the electric power line into the electric power source when the electric communication is formed between the electric power source and the electric power line and the boosted voltage to be supplied to the electric power line is not less than the target voltage, the electric power charged in the battery and/or the voltage booster can be maintained effectively and the excessive amount of the electric power supply from the electric power line into the electric power source is restrained even when the electric power source is electrically connected to the electric power line being active.
It is preferable that the target voltage is more than the voltage of the electric power line. The electric power source may further comprise a supplemental switch device operable to switch on and off the electric power supply from the electric power line into the electric power source, and a voltage step-down circuit operable to decrease a voltage of the electric power supply from the electric power line into the electric power source to be electrically charged into the battery, and the voltage step-down circuit decreases a voltage of the electric power supply from the electric power line into the electric power source when the supplemental switch device allows the electric power supply from the electric power line into the electric power source and the voltage booster is prevented from boosting the voltage.
If the main switch device includes a diode operable to prevent the electric power supply from the electric power line into the electric power source and allow the electric power supply into the electric power line from the electric power source, it is preferable for easily keeping the boosted voltage at a suitable degree that boosting the voltage by the voltage booster is stopped in response to detecting that the diode allows the electric power supply into the electric power line from the electric power source. It is preferable for easily setting the target voltage at a suitable degree that the boosted voltage is equal to the target voltage when the diode allows the electric power supply into the electric power line from the electric power source, when the boosted voltage is kept within a range including the target voltage suitable for the voltage of the electric power source.
The detector may detect a mechanical connection for the electric communication between the electric power source and the electric power line and/or a manual operation of a connector switch operated by an operator when the electric power source is electrically connected to the electric power line.
It is preferable for easily controlling the voltage booster to keep the boosted voltage at the suitable degree that the voltage booster increases a value of the boosted voltage in response to that the boosted voltage is less than the target voltage, and/or in response to detecting that the diode prevents the electric power supply into the electric power line from the electric power source.
It is preferable for keeping the boosted voltage at the suitable degree that the voltage booster boosts the voltage generated by the battery to generate the electric power of boosted voltage when the main switch device allows the electric power supply into the electric power line from the electric power source. It is preferable for restraining an excessive increase of the boosted voltage that the voltage booster is prevented from increasing the value of the boosted voltage in response to detecting that the diode allows the electric power supply into the electric power line from the electric power source. It is preferable that the voltage booster is prevented from increasing the value of the boosted voltage when the boosted voltage is more than the target voltage.
It is preferable for maintaining the electric power charged in the battery and/or the voltage booster effectively that the voltage booster is prevented from increasing the value of the boosted voltage when the electric communication is not formed between the electric power source and the electric power line.
It is preferable for easily setting the target voltage suitable for the electric power line that the target voltage is set at a voltage value of the boosted voltage at which the boosted voltage enables the diode to allow the electric power supply into the electric power line from the voltage booster. If boosting the voltage by the voltage booster is controlled in such a manner that the boosted voltage is kept within a voltage range including the target voltage, the boosted voltage is kept within the voltage range suitable for the electric power line, preferably more than the voltage of the electric power line.